1. Saule Research Institute Wrocław Technology Park, 11 Duńska Wrocław 54‐427 Poland
2. Saule Technologies Wrocław Technology Park, 11 Duńska Wrocław 54‐427 Poland
3. Department of Semiconductor Materials Engineering Wrocław University of Science and Technology Wrocław 50‐370 Poland
4. Faculty of Physics Adam Mickiewicz University Uniwersytetu Poznańskiego 2, Poznań Wrocław 61‐614 Poland